The invention relates to an apparatus for prolonging the life of batteries and, more specifically, to an apparatus and method for reconditioning ear level hearing aid batteries.
Batteries are used in many portable devices today. A very small chemical battery is often used with "in the ear" or "on the ear" type hearing aids. This type of battery generates electricity from the chemical action of an acid or alkali on plates of various metals. This is not to be confused with storage batteries which are only capable of storing electric current charged into them. Successful hearing aid batteries are either the "silver oxide" or "mercury" type. The original chemical battery was a cell comprised of a zinc and a copper plate and immersed in dilute sulfuric acid. One drawback to the use of the chemical battery has been the formation of small bubbles on the zinc element which diminish the flow of current through the cell. Various methods have been devised to delay or remove the polarization of the metallic elements in order that the cell may continue to generate electricity. However, the polarization still plagues all chemical batteries, even though large batteries with large metallic elements are capable of generating a 1.5 volt level for a relatively long time. Unfortunately, the polarization problem is particularly noticeable in very small batteries where the voltage generated drops below the desired 1.5 volt level in a relatively short time. As a result, the small hearing aid batteries have an active lifetime of only five or six days. Their small plates or metallic elements are not exhausted in this short time, but the flow of current is diminished by polarization. These batteries are sold with a warning on the label that they cannot be "recharged" or that they will explode if they are recharged.
For elderly people the cost of repeatedly buying new batteries may become prohibitive. This is particularly true for the individual who is supported by a fixed income. The need to replace the battery in the hearing aid every five or six days also creates problems for users in remote areas of the world, for example, missionaries.
The invention provides a reconditioning device for ear level hearing aid batteries which depolarizes and restores a battery to its original 1.5 volt capacity as long as the metallic elements and the active acid or alkali of the small battery are not exhausted. The device permits a single battery to be reused up to three or four months before a new battery is needed due to loss of chemical action and plate polarization. My life-prolonging device is housed in a box-like container which places the hearing aid battery in parallel with one or more large batteries having a total voltage of exactly 1.5 volts. By this means the hearing aid battery is depolarized and builds up to the same voltage as the larger battery or batteries. Under normal conditions, recharging of the hearing aid battery can take place at night while the user of an ear level hearing aid device is sleeping. Once the hearing aid battery has become completely reconditioned, an equilibrium state is reached wherein no current flows from the larger battery. Thus, no additional energy is wasted. By using my device every night the generating life of the hearing aid battery is prolonged to ten or more times its usual life, depending on the particular miliamperes "draw" of a variety of hearing aids.
When the chemicals or the metallic elements of the hearing aid battery are depleted and the voltage of the battery drops to 1.1 or 1.2 volts, my device will not recharge or restore the worn-out battery. The larger battery eventually will become exhausted too. Therefore, testing apparatus is included in the device to indicate the condition of either battery. Once the lifetime of a battery is completely exhausted, it is simply replaced by another battery.